mac80211/drivers: rewrite the rate control API

So after the previous changes we were still unhappy with how
convoluted the API is and decided to make things simpler for
everybody. This completely changes the rate control API, now
taking into account 802.11n with MCS rates and more control,
most drivers don't support that though.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 179 insertions, 199 deletions

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 6f3e4be97631..21951bac1ef7 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -46,13 +46,20 @@ static __le16 ieee80211_duration(struct ieee80211_tx_data *tx, int group_addr,
         struct ieee80211_local *local = tx->local;
         struct ieee80211_supported_band *sband;
         struct ieee80211_hdr *hdr;
+        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
+
+        /* assume HW handles this */
+        if (info->control.rates[0].flags & IEEE80211_TX_RC_MCS)
+                return 0;
+
+        /* uh huh? */
+        if (WARN_ON_ONCE(info->control.rates[0].idx < 0))
+                return 0;
 
         sband = local->hw.wiphy->bands[tx->channel->band];
-        txrate = &sband->bitrates[tx->rate_idx];
+        txrate = &sband->bitrates[info->control.rates[0].idx];
 
-        erp = 0;
-        if (tx->sdata->flags & IEEE80211_SDATA_OPERATING_GMODE)
-                erp = txrate->flags & IEEE80211_RATE_ERP_G;
+        erp = txrate->flags & IEEE80211_RATE_ERP_G;
 
         /*
          * data and mgmt (except PS Poll):
@@ -437,140 +444,154 @@ ieee80211_tx_h_select_key(struct ieee80211_tx_data *tx)
 static ieee80211_tx_result debug_noinline
 ieee80211_tx_h_rate_ctrl(struct ieee80211_tx_data *tx)
 {
-        struct rate_selection rsel;
-        struct ieee80211_supported_band *sband;
         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
+        struct ieee80211_hdr *hdr = (void *)tx->skb->data;
+        struct ieee80211_supported_band *sband;
+        struct ieee80211_rate *rate;
+        int i, len;
+        bool inval = false, rts = false, short_preamble = false;
+        struct ieee80211_tx_rate_control txrc;
 
-        sband = tx->local->hw.wiphy->bands[tx->channel->band];
+        memset(&txrc, 0, sizeof(txrc));
 
-        if (likely(tx->rate_idx < 0)) {
-                rate_control_get_rate(tx->sdata, sband, tx->sta,
-                                      tx->skb, &rsel);
-                if (tx->sta)
-                        tx->sta->last_txrate_idx = rsel.rate_idx;
-                tx->rate_idx = rsel.rate_idx;
-                if (unlikely(rsel.probe_idx >= 0)) {
-                        info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
-                        tx->flags |= IEEE80211_TX_PROBE_LAST_FRAG;
-                        info->control.retries[0].rate_idx = tx->rate_idx;
-                        info->control.retries[0].limit = tx->local->hw.max_altrate_tries;
-                        tx->rate_idx = rsel.probe_idx;
-                } else if (info->control.retries[0].limit == 0)
-                        info->control.retries[0].rate_idx = -1;
-
-                if (unlikely(tx->rate_idx < 0))
-                        return TX_DROP;
-        } else
-                info->control.retries[0].rate_idx = -1;
+        sband = tx->local->hw.wiphy->bands[tx->channel->band];
 
-        if (tx->sdata->vif.bss_conf.use_cts_prot &&
-            (tx->flags & IEEE80211_TX_FRAGMENTED) && (rsel.nonerp_idx >= 0)) {
-                tx->last_frag_rate_idx = tx->rate_idx;
-                if (rsel.probe_idx >= 0)
-                        tx->flags &= ~IEEE80211_TX_PROBE_LAST_FRAG;
-                else
-                        tx->flags |= IEEE80211_TX_PROBE_LAST_FRAG;
-                tx->rate_idx = rsel.nonerp_idx;
-                info->tx_rate_idx = rsel.nonerp_idx;
-                info->flags &= ~IEEE80211_TX_CTL_RATE_CTRL_PROBE;
-        } else {
-                tx->last_frag_rate_idx = tx->rate_idx;
-                info->tx_rate_idx = tx->rate_idx;
+        len = min_t(int, tx->skb->len + FCS_LEN,
+                         tx->local->fragmentation_threshold);
+
+        /* set up the tx rate control struct we give the RC algo */
+        txrc.hw = local_to_hw(tx->local);
+        txrc.sband = sband;
+        txrc.bss_conf = &tx->sdata->vif.bss_conf;
+        txrc.skb = tx->skb;
+        txrc.reported_rate.idx = -1;
+        txrc.max_rate_idx = tx->sdata->max_ratectrl_rateidx;
+
+        /* set up RTS protection if desired */
+        if (tx->local->rts_threshold < IEEE80211_MAX_RTS_THRESHOLD &&
+            len > tx->local->rts_threshold) {
+                txrc.rts = rts = true;
         }
-        info->tx_rate_idx = tx->rate_idx;
 
-        return TX_CONTINUE;
-}
+        /*
+         * Use short preamble if the BSS can handle it, but not for
+         * management frames unless we know the receiver can handle
+         * that -- the management frame might be to a station that
+         * just wants a probe response.
+         */
+        if (tx->sdata->vif.bss_conf.use_short_preamble &&
+            (ieee80211_is_data(hdr->frame_control) ||
+             (tx->sta && test_sta_flags(tx->sta, WLAN_STA_SHORT_PREAMBLE))))
+                txrc.short_preamble = short_preamble = true;
 
-static ieee80211_tx_result debug_noinline
-ieee80211_tx_h_misc(struct ieee80211_tx_data *tx)
-{
-        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)tx->skb->data;
-        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
-        struct ieee80211_supported_band *sband;
 
-        sband = tx->local->hw.wiphy->bands[tx->channel->band];
+        rate_control_get_rate(tx->sdata, tx->sta, &txrc);
+
+        if (unlikely(info->control.rates[0].idx < 0))
+                return TX_DROP;
+
+        if (txrc.reported_rate.idx < 0)
+                txrc.reported_rate = info->control.rates[0];
 
         if (tx->sta)
-                info->control.sta = &tx->sta->sta;
+                tx->sta->last_tx_rate = txrc.reported_rate;
 
-        if (!info->control.retry_limit) {
-                if (!is_multicast_ether_addr(hdr->addr1)) {
-                        int len = min_t(int, tx->skb->len + FCS_LEN,
-                                        tx->local->fragmentation_threshold);
-                        if (len > tx->local->rts_threshold
-                            && tx->local->rts_threshold <
-                                                IEEE80211_MAX_RTS_THRESHOLD) {
-                                info->flags |= IEEE80211_TX_CTL_USE_RTS_CTS;
-                                info->flags |=
-                                        IEEE80211_TX_CTL_LONG_RETRY_LIMIT;
-                                info->control.retry_limit =
-                                        tx->local->hw.conf.long_frame_max_tx_count - 1;
-                        } else {
-                                info->control.retry_limit =
-                                        tx->local->hw.conf.short_frame_max_tx_count - 1;
-                        }
-                } else {
-                        info->control.retry_limit = 1;
-                }
-        }
+        if (unlikely(!info->control.rates[0].count))
+                info->control.rates[0].count = 1;
 
-        if (tx->flags & IEEE80211_TX_FRAGMENTED) {
-                /* Do not use multiple retry rates when sending fragmented
-                 * frames.
-                 * TODO: The last fragment could still use multiple retry
-                 * rates. */
-                info->control.retries[0].rate_idx = -1;
+        if (is_multicast_ether_addr(hdr->addr1)) {
+                /*
+                 * XXX: verify the rate is in the basic rateset
+                 */
+                return TX_CONTINUE;
         }
 
-        /* Use CTS protection for unicast frames sent using extended rates if
-         * there are associated non-ERP stations and RTS/CTS is not configured
-         * for the frame. */
-        if ((tx->sdata->flags & IEEE80211_SDATA_OPERATING_GMODE) &&
-            (sband->bitrates[tx->rate_idx].flags & IEEE80211_RATE_ERP_G) &&
-            (tx->flags & IEEE80211_TX_UNICAST) &&
-            tx->sdata->vif.bss_conf.use_cts_prot &&
-            !(info->flags & IEEE80211_TX_CTL_USE_RTS_CTS))
-                info->flags |= IEEE80211_TX_CTL_USE_CTS_PROTECT;
-
-        /* Transmit data frames using short preambles if the driver supports
-         * short preambles at the selected rate and short preambles are
-         * available on the network at the current point in time. */
-        if (ieee80211_is_data(hdr->frame_control) &&
-            (sband->bitrates[tx->rate_idx].flags & IEEE80211_RATE_SHORT_PREAMBLE) &&
-            tx->sdata->vif.bss_conf.use_short_preamble &&
-            (!tx->sta || test_sta_flags(tx->sta, WLAN_STA_SHORT_PREAMBLE))) {
-                info->flags |= IEEE80211_TX_CTL_SHORT_PREAMBLE;
+        /*
+         * set up the RTS/CTS rate as the fastest basic rate
+         * that is not faster than the data rate
+         *
+         * XXX: Should this check all retry rates?
+         */
+        if (!(info->control.rates[0].flags & IEEE80211_TX_RC_MCS)) {
+                s8 baserate = 0;
+
+                rate = &sband->bitrates[info->control.rates[0].idx];
+
+                for (i = 0; i < sband->n_bitrates; i++) {
+                        /* must be a basic rate */
+                        if (!(tx->sdata->vif.bss_conf.basic_rates & BIT(i)))
+                                continue;
+                        /* must not be faster than the data rate */
+                        if (sband->bitrates[i].bitrate > rate->bitrate)
+                                continue;
+                        /* maximum */
+                        if (sband->bitrates[baserate].bitrate <
+                             sband->bitrates[i].bitrate)
+                                baserate = i;
+                }
+
+                info->control.rts_cts_rate_idx = baserate;
         }
 
-        if ((info->flags & IEEE80211_TX_CTL_USE_RTS_CTS) ||
-            (info->flags & IEEE80211_TX_CTL_USE_CTS_PROTECT)) {
-                struct ieee80211_rate *rate;
-                s8 baserate = -1;
-                int idx;
+        for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
+                /*
+                 * make sure there's no valid rate following
+                 * an invalid one, just in case drivers don't
+                 * take the API seriously to stop at -1.
+                 */
+                if (inval) {
+                        info->control.rates[i].idx = -1;
+                        continue;
+                }
+                if (info->control.rates[i].idx < 0) {
+                        inval = true;
+                        continue;
+                }
 
-                /* Do not use multiple retry rates when using RTS/CTS */
-                info->control.retries[0].rate_idx = -1;
+                /*
+                 * For now assume MCS is already set up correctly, this
+                 * needs to be fixed.
+                 */
+                if (info->control.rates[i].flags & IEEE80211_TX_RC_MCS) {
+                        WARN_ON(info->control.rates[i].idx > 76);
+                        continue;
+                }
 
-                /* Use min(data rate, max base rate) as CTS/RTS rate */
-                rate = &sband->bitrates[tx->rate_idx];
+                /* set up RTS protection if desired */
+                if (rts)
+                        info->control.rates[i].flags |=
+                                IEEE80211_TX_RC_USE_RTS_CTS;
 
-                for (idx = 0; idx < sband->n_bitrates; idx++) {
-                        if (sband->bitrates[idx].bitrate > rate->bitrate)
-                                continue;
-                        if (tx->sdata->vif.bss_conf.basic_rates & BIT(idx) &&
-                            (baserate < 0 ||
-                             (sband->bitrates[baserate].bitrate
-                              < sband->bitrates[idx].bitrate)))
-                                baserate = idx;
+                /* RC is busted */
+                if (WARN_ON(info->control.rates[i].idx >=
+                            sband->n_bitrates)) {
+                        info->control.rates[i].idx = -1;
+                        continue;
                 }
 
-                if (baserate >= 0)
-                        info->control.rts_cts_rate_idx = baserate;
-                else
-                        info->control.rts_cts_rate_idx = 0;
+                rate = &sband->bitrates[info->control.rates[i].idx];
+
+                /* set up short preamble */
+                if (short_preamble &&
+                    rate->flags & IEEE80211_RATE_SHORT_PREAMBLE)
+                        info->control.rates[i].flags |=
+                                IEEE80211_TX_RC_USE_SHORT_PREAMBLE;
+
+                /* set up G protection */
+                if (!rts && tx->sdata->vif.bss_conf.use_cts_prot &&
+                    rate->flags & IEEE80211_RATE_ERP_G)
+                        info->control.rates[i].flags |=
+                                IEEE80211_TX_RC_USE_CTS_PROTECT;
         }
 
+        return TX_CONTINUE;
+}
+
+static ieee80211_tx_result debug_noinline
+ieee80211_tx_h_misc(struct ieee80211_tx_data *tx)
+{
+        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
+
         if (tx->sta)
                 info->control.sta = &tx->sta->sta;
 
@@ -678,6 +699,7 @@ ieee80211_tx_h_fragment(struct ieee80211_tx_data *tx)
         left = payload_len - per_fragm;
         for (i = 0; i < num_fragm - 1; i++) {
                 struct ieee80211_hdr *fhdr;
+                struct ieee80211_tx_info *info;
                 size_t copylen;
 
                 if (left <= 0)
@@ -692,20 +714,45 @@ ieee80211_tx_h_fragment(struct ieee80211_tx_data *tx)
                                       IEEE80211_ENCRYPT_TAILROOM);
                 if (!frag)
                         goto fail;
+
                 /* Make sure that all fragments use the same priority so
                  * that they end up using the same TX queue */
                 frag->priority = first->priority;
+
                 skb_reserve(frag, tx->local->tx_headroom +
                                   IEEE80211_ENCRYPT_HEADROOM);
+
+                /* copy TX information */
+                info = IEEE80211_SKB_CB(frag);
+                memcpy(info, first->cb, sizeof(frag->cb));
+
+                /* copy/fill in 802.11 header */
                 fhdr = (struct ieee80211_hdr *) skb_put(frag, hdrlen);
                 memcpy(fhdr, first->data, hdrlen);
-                if (i == num_fragm - 2)
-                        fhdr->frame_control &= cpu_to_le16(~IEEE80211_FCTL_MOREFRAGS);
                 fhdr->seq_ctrl = cpu_to_le16(seq | ((i + 1) & IEEE80211_SCTL_FRAG));
+
+                if (i == num_fragm - 2) {
+                        /* clear MOREFRAGS bit for the last fragment */
+                        fhdr->frame_control &= cpu_to_le16(~IEEE80211_FCTL_MOREFRAGS);
+                } else {
+                        /*
+                         * No multi-rate retries for fragmented frames, that
+                         * would completely throw off the NAV at other STAs.
+                         */
+                        info->control.rates[1].idx = -1;
+                        info->control.rates[2].idx = -1;
+                        info->control.rates[3].idx = -1;
+                        info->control.rates[4].idx = -1;
+                        BUILD_BUG_ON(IEEE80211_TX_MAX_RATES != 5);
+                        info->flags &= ~IEEE80211_TX_CTL_RATE_CTRL_PROBE;
+                }
+
+                /* copy data */
                 copylen = left > per_fragm ? per_fragm : left;
                 memcpy(skb_put(frag, copylen), pos, copylen);
-                memcpy(frag->cb, first->cb, sizeof(frag->cb));
+
                 skb_copy_queue_mapping(frag, first);
+
                 frag->do_not_encrypt = first->do_not_encrypt;
 
                 pos += copylen;
@@ -765,12 +812,10 @@ ieee80211_tx_h_calculate_duration(struct ieee80211_tx_data *tx)
                                               tx->extra_frag[0]->len);
 
         for (i = 0; i < tx->num_extra_frag; i++) {
-                if (i + 1 < tx->num_extra_frag) {
+                if (i + 1 < tx->num_extra_frag)
                         next_len = tx->extra_frag[i + 1]->len;
-                } else {
+                else
                         next_len = 0;
-                        tx->rate_idx = tx->last_frag_rate_idx;
-                }
 
                 hdr = (struct ieee80211_hdr *)tx->extra_frag[i]->data;
                 hdr->duration_id = ieee80211_duration(tx, 0, next_len);
@@ -823,7 +868,6 @@ __ieee80211_parse_tx_radiotap(struct ieee80211_tx_data *tx,
                 (struct ieee80211_radiotap_header *) skb->data;
         struct ieee80211_supported_band *sband;
         int ret = ieee80211_radiotap_iterator_init(&iterator, rthdr, skb->len);
-        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 
         sband = tx->local->hw.wiphy->bands[tx->channel->band];
 
@@ -837,8 +881,6 @@ __ieee80211_parse_tx_radiotap(struct ieee80211_tx_data *tx,
          */
 
         while (!ret) {
-                int i, target_rate;
-
                 ret = ieee80211_radiotap_iterator_next(&iterator);
 
                 if (ret)
@@ -852,38 +894,6 @@ __ieee80211_parse_tx_radiotap(struct ieee80211_tx_data *tx,
                  * get_unaligned((type *)iterator.this_arg) to dereference
                  * iterator.this_arg for type "type" safely on all arches.
                 */
-                case IEEE80211_RADIOTAP_RATE:
-                        /*
-                         * radiotap rate u8 is in 500kbps units eg, 0x02=1Mbps
-                         * ieee80211 rate int is in 100kbps units eg, 0x0a=1Mbps
-                         */
-                        target_rate = (*iterator.this_arg) * 5;
-                        for (i = 0; i < sband->n_bitrates; i++) {
-                                struct ieee80211_rate *r;
-
-                                r = &sband->bitrates[i];
-
-                                if (r->bitrate == target_rate) {
-                                        tx->rate_idx = i;
-                                        break;
-                                }
-                        }
-                        break;
-
-                case IEEE80211_RADIOTAP_ANTENNA:
-                        /*
-                         * radiotap uses 0 for 1st ant, mac80211 is 1 for
-                         * 1st ant
-                         */
-                        info->antenna_sel_tx = (*iterator.this_arg) + 1;
-                        break;
-
-#if 0
-                case IEEE80211_RADIOTAP_DBM_TX_POWER:
-                        control->power_level = *iterator.this_arg;
-                        break;
-#endif
-
                 case IEEE80211_RADIOTAP_FLAGS:
                         if (*iterator.this_arg & IEEE80211_RADIOTAP_F_FCS) {
                                 /*
@@ -949,8 +959,6 @@ __ieee80211_tx_prepare(struct ieee80211_tx_data *tx,
         tx->local = local;
         tx->sdata = IEEE80211_DEV_TO_SUB_IF(dev);
         tx->channel = local->hw.conf.channel;
-        tx->rate_idx = -1;
-        tx->last_frag_rate_idx = -1;
         /*
          * Set this flag (used below to indicate "automatic fragmentation"),
          * it will be cleared/left by radiotap as desired.
@@ -1051,23 +1059,11 @@ static int __ieee80211_tx(struct ieee80211_local *local, struct sk_buff *skb,
                         if (!tx->extra_frag[i])
                                 continue;
                         info = IEEE80211_SKB_CB(tx->extra_frag[i]);
-                        info->flags &= ~(IEEE80211_TX_CTL_USE_RTS_CTS |
-                                         IEEE80211_TX_CTL_USE_CTS_PROTECT |
-                                         IEEE80211_TX_CTL_CLEAR_PS_FILT |
+                        info->flags &= ~(IEEE80211_TX_CTL_CLEAR_PS_FILT |
                                          IEEE80211_TX_CTL_FIRST_FRAGMENT);
                         if (netif_subqueue_stopped(local->mdev,
                                                    tx->extra_frag[i]))
                                 return IEEE80211_TX_FRAG_AGAIN;
-                        if (i == tx->num_extra_frag) {
-                                info->tx_rate_idx = tx->last_frag_rate_idx;
-
-                                if (tx->flags & IEEE80211_TX_PROBE_LAST_FRAG)
-                                        info->flags |=
-                                                IEEE80211_TX_CTL_RATE_CTRL_PROBE;
-                                else
-                                        info->flags &=
-                                                ~IEEE80211_TX_CTL_RATE_CTRL_PROBE;
-                        }
 
                         ret = local->ops->tx(local_to_hw(local),
                                             tx->extra_frag[i]);
@@ -1204,9 +1200,6 @@ retry:
                 store->skb = skb;
                 store->extra_frag = tx.extra_frag;
                 store->num_extra_frag = tx.num_extra_frag;
-                store->last_frag_rate_idx = tx.last_frag_rate_idx;
-                store->last_frag_rate_ctrl_probe =
-                        !!(tx.flags & IEEE80211_TX_PROBE_LAST_FRAG);
         }
  out:
         rcu_read_unlock();
@@ -1763,10 +1756,7 @@ void ieee80211_tx_pending(unsigned long data)
                 store = &local->pending_packet[i];
                 tx.extra_frag = store->extra_frag;
                 tx.num_extra_frag = store->num_extra_frag;
-                tx.last_frag_rate_idx = store->last_frag_rate_idx;
                 tx.flags = 0;
-                if (store->last_frag_rate_ctrl_probe)
-                        tx.flags |= IEEE80211_TX_PROBE_LAST_FRAG;
                 ret = __ieee80211_tx(local, store->skb, &tx);
                 if (ret) {
                         if (ret == IEEE80211_TX_FRAG_AGAIN)
@@ -1854,7 +1844,6 @@ struct sk_buff *ieee80211_beacon_get(struct ieee80211_hw *hw,
         struct ieee80211_sub_if_data *sdata = NULL;
         struct ieee80211_if_ap *ap = NULL;
         struct ieee80211_if_sta *ifsta = NULL;
-        struct rate_selection rsel;
         struct beacon_data *beacon;
         struct ieee80211_supported_band *sband;
         enum ieee80211_band band = local->hw.conf.channel->band;
@@ -1958,32 +1947,23 @@ struct sk_buff *ieee80211_beacon_get(struct ieee80211_hw *hw,
         skb->do_not_encrypt = 1;
 
         info->band = band;
-        rate_control_get_rate(sdata, sband, NULL, skb, &rsel);
-
-        if (unlikely(rsel.rate_idx < 0)) {
-                if (net_ratelimit()) {
-                        printk(KERN_DEBUG "%s: ieee80211_beacon_get: "
-                               "no rate found\n",
-                               wiphy_name(local->hw.wiphy));
-                }
-                dev_kfree_skb_any(skb);
-                skb = NULL;
-                goto out;
-        }
+        /*
+         * XXX: For now, always use the lowest rate
+         */
+        info->control.rates[0].idx = 0;
+        info->control.rates[0].count = 1;
+        info->control.rates[1].idx = -1;
+        info->control.rates[2].idx = -1;
+        info->control.rates[3].idx = -1;
+        info->control.rates[4].idx = -1;
+        BUILD_BUG_ON(IEEE80211_TX_MAX_RATES != 5);
 
         info->control.vif = vif;
-        info->tx_rate_idx = rsel.rate_idx;
 
         info->flags |= IEEE80211_TX_CTL_NO_ACK;
         info->flags |= IEEE80211_TX_CTL_CLEAR_PS_FILT;
         info->flags |= IEEE80211_TX_CTL_ASSIGN_SEQ;
-        if (sdata->vif.bss_conf.use_short_preamble &&
-            sband->bitrates[rsel.rate_idx].flags & IEEE80211_RATE_SHORT_PREAMBLE)
-                info->flags |= IEEE80211_TX_CTL_SHORT_PREAMBLE;
-
-        info->control.retry_limit = 1;
-
-out:
+ out:
         rcu_read_unlock();
         return skb;
 }